A problem facing many manufacturing and industrial facilities is efficient and economical disposal of waste products. Many waste products in manufacturing operations are aqueous or organic solvent semi-solid solutions commonly referred to as sludge. A dramatic reduction in volume of sludge can be realized by drying the sludge to dry water and solvents.
In my prior art patent, U.S. Pat. No. 4,815,397, entitled Sludge Treatment Apparatus, I proposed a sludge drying apparatus in which sludge is conveyed on a screen conveyor in close proximity to ceramic thermal reactors. Ambient air is drawn through each reactor by a fan which directs air across a pair of ceramic burners. The pair of ceramic burners of each reactor are separated from adjacent reactors. Air drawn through the sludge and screen conveyor is supplied to the sludge inlet area in an attempt to preheat the sludge. One problem regarding this apparatus is its low energy efficiency. Also, air directed toward the incoming sludge was not contained within the unit, and resulted in unacceptable levels of particulate and combustion byproducts being released into the environment around the sludge treatment apparatus.
The throughput or drying capacity of the prior sludge drier was limited in capacity to approximately 35 pounds per hour. Running the drier at higher throughput rates was not possible due to uneven heating and inefficient operation of thermal reactors. To achieve optimum drying, a substantially uniform temperature profile should be maintained in the drier. In addition to a uniform temperature profile, uniform air flow in the drier section improves overall drying efficiency. It has been found that uniform temperature conditions and air flow were not possible with the use of individual thermal reactors operating independently of each other. Effective recirculation of heated air was not achieved by the prior apparatus.
These and other problems relating to the prior art are addressed by the present invention.